Underexpression of CACNA1C Caused by Overexpression of microRNA-29a Underlies the Pathogenesis of Atrial Fibrillation.

BACKGROUND The objective of this study was to investigate the molecular mechanism of atrial fibrillation (AF), as well as the negative regulatory relationship between miR-29a-3p and CACNA1C. MATERIAL AND METHODS We searched the online miRNA database (www.mirdb.org) and identified the miR-29a-3p binding sequence within the 3'-UTR of the target gene, and then conducted luciferase assay to verify it. The cells were transfected with miR-29a-3p and ICa,L was determined in those cells. RESULTS We validated CACNA1C to be the direct target gene of miR-29a-3p. We also established the negative regulatory relationship between miR-29a-3p and CACNA1C via studying the relative luciferase activity. We also conducted real-time PCR and Western blot analysis to study the mRNA and protein expression level of CACNA1C among different groups of cells treated with scramble control, 30nM miR-29a-3p mimics, and 60nM miR-29a-3p mimics, indicating a negative regulatory relationship between miR-29a-3p and CACNA1C. We next analyzed whether miR-29a-3p transfection in cardiomyocytes produced the effects on the ICa,L induced by electrical remodeling, and found a tonic inhibition of IBa by endogenous miR-29a-3p in atrial myocytes. CONCLUSIONS We validated the negative regulation between miR-29a-3p and CACNA1C, and found that miR-29a-3p might a potential therapeutic target in the treatment of AF.